Containers for storage or transport of temperature sensitive materials, such as biomaterials, may use a phase change material (“PCM”) to maintain a desired temperature for preserving the sensitive material. Water is one of the most used PCMs for many temperature control applications and is normally used to keep the temperature of an environment close to zero degrees Celsius (0° C.), the freezing or phase change temperature for water. However, certain biomaterials and other temperature sensitive materials are often damaged when stored close to 0° C. and therefore should be stored at temperatures somewhat greater than 0° C. and less than approximately 4° C. It is well known and understood that the addition of a material, such as salt, to water (H2O), provides a mixture with a freezing temperature below 0° C. In general, the addition of a material to water usually depresses or lowers the mixture's phase change temperature.
Although there is a variation in the ranges of desirable temperatures for passive storage and transport, there is a particular need for temperature values from around 0° C. to about 4° C. For example, in transport of biomaterials such as proteins, vaccines, transplant organs, blood products, urine samples, and other similar materials values too close to 0° C. or greater than approximately 4° C. may cause degradation of the biomaterials.
When a PCM has a phase change temperature, the temperature where freezing occurs, near or less than 0° C. the PCM is generally not useful for providing passive temperature control for biomaterials requiring storage temperatures slightly greater than 0° C. Because water has an excellent heat of fusion, water is generally considered to be a prime component for a PCM mixture. It would be desirable to find a material that when added to water would result in a mixture that had an increased phase change temperature that was greater than 0° C. and had a heat of fusion value nearly equal to that of water. Further, it would be desirable if such a material was relatively inexpensive, readily available, and non-toxic. Another desirable attribute of such a material would be the attribute of easily forming a homogeneous mixture with water. It would also be desirable if the added material had other physical characteristics similar to water.